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Initial commit of OpenSPARC T2 architecture model.
[OpenSPARC-T2-SAM] / sam-t2 / devtools / amd64 / html / python / lib / itertools-recipes.html
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54<H2><A NAME="SECTION0071630000000000000000"></A><A NAME="itertools-recipes"></A>
55<BR>
565.16.3 Recipes
57</H2>
58
59<P>
60This section shows recipes for creating an extended toolset using the
61existing itertools as building blocks.
62
63<P>
64The extended tools offer the same high performance as the underlying
65toolset. The superior memory performance is kept by processing elements one
66at a time rather than bringing the whole iterable into memory all at once.
67Code volume is kept small by linking the tools together in a functional style
68which helps eliminate temporary variables. High speed is retained by
69preferring ``vectorized'' building blocks over the use of for-loops and
70generators which incur interpreter overhead.
71
72<P>
73<div class="verbatim"><pre>
74def take(n, seq):
75 return list(islice(seq, n))
76
77def enumerate(iterable):
78 return izip(count(), iterable)
79
80def tabulate(function):
81 "Return function(0), function(1), ..."
82 return imap(function, count())
83
84def iteritems(mapping):
85 return izip(mapping.iterkeys(), mapping.itervalues())
86
87def nth(iterable, n):
88 "Returns the nth item"
89 return list(islice(iterable, n, n+1))
90
91def all(seq, pred=bool):
92 "Returns True if pred(x) is True for every element in the iterable"
93 for elem in ifilterfalse(pred, seq):
94 return False
95 return True
96
97def any(seq, pred=bool):
98 "Returns True if pred(x) is True for at least one element in the iterable"
99 for elem in ifilter(pred, seq):
100 return True
101 return False
102
103def no(seq, pred=bool):
104 "Returns True if pred(x) is False for every element in the iterable"
105 for elem in ifilter(pred, seq):
106 return False
107 return True
108
109def quantify(seq, pred=bool):
110 "Count how many times the predicate is True in the sequence"
111 return sum(imap(pred, seq))
112
113def padnone(seq):
114 """Returns the sequence elements and then returns None indefinitely.
115
116 Useful for emulating the behavior of the built-in map() function.
117 """
118 return chain(seq, repeat(None))
119
120def ncycles(seq, n):
121 "Returns the sequence elements n times"
122 return chain(*repeat(seq, n))
123
124def dotproduct(vec1, vec2):
125 return sum(imap(operator.mul, vec1, vec2))
126
127def flatten(listOfLists):
128 return list(chain(*listOfLists))
129
130def repeatfunc(func, times=None, *args):
131 """Repeat calls to func with specified arguments.
132
133 Example: repeatfunc(random.random)
134 """
135 if times is None:
136 return starmap(func, repeat(args))
137 else:
138 return starmap(func, repeat(args, times))
139
140def pairwise(iterable):
141 "s -&gt; (s0,s1), (s1,s2), (s2, s3), ..."
142 a, b = tee(iterable)
143 try:
144 b.next()
145 except StopIteration:
146 pass
147 return izip(a, b)
148</pre></div>
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Full OpenSPARC architecture tarball including simulator, hypervisor, and OBP.